polygon_collision.cpp

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// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#include "test.h"

class PolygonCollision : public Test
{
public:
        PolygonCollision()
        {
                {
                        m_polygonA.SetAsBox(0.2f, 0.4f);
                        m_transformA.Set(b2Vec2(0.0f, 0.0f), 0.0f);
                }

                {
                        m_polygonB.SetAsBox(0.5f, 0.5f);
                        m_positionB.Set(19.345284f, 1.5632932f);
                        m_angleB = 1.9160721f;
                        m_transformB.Set(m_positionB, m_angleB);
                }
        }

        static Test* Create()
        {
                return new PolygonCollision;
        }

        void Step(Settings& settings) override
        {
                B2_NOT_USED(settings);

                b2Manifold manifold;
                b2CollidePolygons(&manifold, &m_polygonA, m_transformA, &m_polygonB, m_transformB);

                b2WorldManifold worldManifold;
                worldManifold.Initialize(&manifold, m_transformA, m_polygonA.m_radius, m_transformB, m_polygonB.m_radius);

                g_debugDraw.DrawString(5, m_textLine, "point count = %d", manifold.pointCount);
                m_textLine += m_textIncrement;

                {
                        b2Color color(0.9f, 0.9f, 0.9f);
                        b2Vec2 v[b2_maxPolygonVertices];
                        for (int32 i = 0; i < m_polygonA.m_count; ++i)
                        {
                                v[i] = b2Mul(m_transformA, m_polygonA.m_vertices[i]);
                        }
                        g_debugDraw.DrawPolygon(v, m_polygonA.m_count, color);

                        for (int32 i = 0; i < m_polygonB.m_count; ++i)
                        {
                                v[i] = b2Mul(m_transformB, m_polygonB.m_vertices[i]);
                        }
                        g_debugDraw.DrawPolygon(v, m_polygonB.m_count, color);
                }

                for (int32 i = 0; i < manifold.pointCount; ++i)
                {
                        g_debugDraw.DrawPoint(worldManifold.points[i], 4.0f, b2Color(0.9f, 0.3f, 0.3f));
                }

                Test::Step(settings);
        }

        void Keyboard(int key) override
        {
                switch (key)
                {
                case GLFW_KEY_A:
                        m_positionB.x -= 0.1f;
                        break;

                case GLFW_KEY_D:
                        m_positionB.x += 0.1f;
                        break;

                case GLFW_KEY_S:
                        m_positionB.y -= 0.1f;
                        break;

                case GLFW_KEY_W:
                        m_positionB.y += 0.1f;
                        break;

                case GLFW_KEY_Q:
                        m_angleB += 0.1f * b2_pi;
                        break;

                case GLFW_KEY_E:
                        m_angleB -= 0.1f * b2_pi;
                        break;
                }

                m_transformB.Set(m_positionB, m_angleB);
        }

        b2PolygonShape m_polygonA;
        b2PolygonShape m_polygonB;

        b2Transform m_transformA;
        b2Transform m_transformB;

        b2Vec2 m_positionB;
        float m_angleB;
};

static int testIndex = RegisterTest("Geometry", "Polygon Collision", PolygonCollision::Create);